1993 Toyota Camry FRONT DISC LOCKING

The first thing I would suspect is the proportoining valve.
Then, I would loo at the caliper.
This is the front left caliper that is the only one locking up?
It can lock up on the shafts that the caliper slideson. Especially after it has happended once, it will happen over and over. Even if you straightenthe pin, I would think itis fatiguedand the caliper needs to be replacedif this is the case.

Let meknow howit goes and ifIcan help any furhter.

If the master cylinder were the culprit, I could see the seal being seated incorrectly and closing over the port and not releasing the pressure built up. However, This would affect both front brakes or both back brakes.
Again, this is the front driver's side claiper, correct?
That is the closest to the master cylinder. Keepthat in mind as we go through this. Not that I know that it is part of the puzzle.
Did this happen as soon as the brakes were done and you first used them?
If not, how long before this happened?

Let me know and I will think some more about it.
By process of eleimination, you are kind of getting down to the master cylinder aren't you?
However, make sure that the cliper that is locking up get checked over or replced as the pins it floats o arre probably bent and the pads are ertainlydamaged.

I will check backlater.

Before the problem reoccured, how long after the first caliper was put on before it had its first failure?
Was it an orignal caliper on the car or one tht you had put on that failed.
I just want to really clarify, communicating by text is not easy, so we don't misunderstand each other.
So forgive me if I ask things I have already asked or that may seem already evident.

So, first before you started working on the brakes and the system was from the factory, if it was not the original let me know, were there problems with the caliper then?

If not, I am assuming and correct me where I am wrong, part of the brake project that you originally did was the following;

Both front calipers

Front brake pads
Are the rear brakes drums or pads? Were the rear calipers/wheel cylinders replaced at that time?

Rear pads/shoes

System fluid was replaced and bled starting at the passenger rear, then drivers rear, then passenger front and lastly drivers front. This is order of farthest to closest from master cylinder.

Then the 1 caliper locked up. After a period of time it freed up. How long before it locked up again and how did the brakes perform before that happened?

Then the proportioning valve was replaced. The caliper that was locked was not replaced. Did you inspect it and if so what did it look like?

Then locked again, same questions as above?

I am sorry about the redundancy. I just want to understand the timeline and what was replaced or failed and when in this sequence of events.

I think you will certainly have to replace the caliper, but I think that if it was remanufactured it probably has a warranty. So, try to get another without paying for it.

Hold off on replacing it because if I understand correctly, you have purchased 2 calipers that were defective. The odds are slim on that.
There is something else going on and I would hate to see you install another caliper and have it lock up.

I will check back soon. It will work out.

I do not think that the pads are the source unless you got something defective or really cheap. Just increasing the likelihood of a defective issue. In either case, I agree it is odd and is probably not the reason for the problem.
I would not rule it out, but something in the caliper is more likely.
Unfortunately, now that it has locked up once, the original reason that caused it could be covered by the damage that the locked caliper has caused to the pads and caliper.
I would get a new caliper through warranty and buy a new set of pads. However I am apprehensive to install them as of yet because if they were not the original source for the problem, they will be damaged and need replacing again without gaining any insight into the source of the problem.

I am going to do some research and put some more thought into the issue.

Go ahead and try getting replacements through warranty, but don't install them until we can get some more insight into the problem. You should only have to carry the core cost on the caliper for a while.

I will get back with some answers ASAP. Let me know what you find out and we will get you there.

I will be checking the posts as much as I can untill I see what comes from changing the hardware issue you found.

That is great news. I am so glad to hear that it worked out without having to spend any more money or time.

I forget how many miles are on the car, but just a few thoughts that I have found that will certainly get almost any car to get that many miles on it.

If your car has more than 50,000 miles on it, synthetic oils can cause more harm than good. The reason for this is that synthetics can cause leaks because it lubricates too well that it will slip past rings and leak around seals.

The most important things are changing motor oil, tranny oil, flushing the brake fluid, flushing the anti-freeze, flushing the power steering fluid and running fuel injector cleaner.

You do not need to get expensive motor oil, just the correct weight and a brand that is well known such as Valvoline or Penzoil for example. It is also important to use either an OEM Oil. Filter or a good brand that has an anti-drain back valve. This is important because not having an anti-drain back valve will cause top end damage during start up. I bought a Fram filter once that did not have this valve and my car sounded like it was going to blow up when I started it. OEM or Purolator filters are good, just make sure the filter has the valve.

Tranny fluid is the same with about a 30,000 mile interval, but it depends on manufacturer guidelines and driving conditions which are refered to in the guidelines as well.

Brake fluid is about the same interval and is important because it will get water in it and cause corrosion and damage lines that cost a great deal of money to replace.

Anti-freeze loses it cooling and ability to keep the water that is mixed in, always use a 50/50 mixture from condensing and freezing. It needs to be completely flushed, replaced and the system bled so it is free from air that will cause cooling problems. It is also a lubricant that keeps parts form corroding and losses its lubrication qualities as well. Also, thermostats and radiator caps can cause issues.

Power steering fluid is very rarely needed, but certainly follow manufacturer guidelines because you intend to keep it so long. Be careful when changing ti as it needs some fluid in it to keep it from damaging internal parts. So when you flush it, don't drain it till it is completely dry.

Lastly, fuel injector cleaner is important and is something to do right before an oil change as it will make the oil dirty. I use BG44K and it is the best at keeping the motor clean and fuel injectors running right. Also, keep up another items that the manufacturer suggest.

This all sounds like a lot to keep up on. But it is true that $100 in maintenance saves $1000 in repair.

I always check posts regularly and I will keep the link to this post in my list. If you need anything feel free to PM me as well.

I am glad it all worked out and it always will as long as you believe in blessings, good things are sure to come.

Take care.

Sorrry it did not completely work out. But, you made a big leap in finding out what is causing the problem. Just the fact that it did not lock up as soon and that the caliper was stuck in place says that that is the source for the problem.
First try taking off the caliper and seeing if it moves on the pins that allow it to move on the part of tyhe caliper that is bolted to the steering knuckle. My first instinct is that they have been bent when the caliper was locking up. Sounds like some hardware got switched around somehow between the 2 calipers you have bought and installed. This makes me think that one of the 2 were not the right caliper. I say that becasue if they were both the right caliper, there should not be any issues with trading out the hardware. So, I think somewhere along the line, you were given the wrong caliper, the hardware from the caliper, (that was sold to you incorrectly), got mixed up in the tradeoff, maybe the problem started when you were sold the incorrect caliper and you now have a mess on your hands and now I think you are best off starting from scratch. Sorta.
So, regardless of anything, the caliper you have is probaly damaged from locking up and should be replaced. If you are holdoing on to another caliper, compare the 2 because I think you were given one that does not fiot your car. Next try to either exchange the caliper that you were sold, (if there is indeed one that you find to be incorrect), or try to use the manufacturer warranty to replace it so you don't spend any more money.

Let me know how this goes.
Don't let it frustrate you because I am sure you are on the right path and it will work out.